CNBC host John Harwood in September 2015 asked Hillary Clinton's campaign chairman, John Podesta, what he should ask then-Republican presidential candidate former Florida Gov. Jeb Bush in an upcoming interview, according to new emails published by WikiLeaks.

Harwood, who faced harsh criticism for his performance as a debate moderator in the third Republican presidential primary debate in October 2015, sent Podesta an email on Sept. 21, 2015, with the subject line, "What should I ask Jeb..." The body of the email read, "...in Speakeasy interview tomorrow."

Image source: WIkiLeaks

Harwood interviewed Bush in a diner four days later.

A little more than a month after the interview, Harwood co-moderated the CNBC Republican presidential primary debate, which was widely criticized, including by Republican National Committee Chairman Reince Priebus.

"CNBC should be ashamed of how this debate was handled," Priebus tweeted the night of the Oct. 28, 2015, debate.

On Monday, the Hill columnist Joe Concha called out Harwood, saying his newly revealed email to Podesta amounts to "campaign collusion."

The optics of Harwood advising a presidential campaign while allowing the campaign to write questions for his network are not only horrible, but the hubris he displayed afterward is a huge turnoff to at least half of CNBC’s audience, which now views Harwood as a comic-book version of a chief Washington correspondent.

Concha was referring to another email Harwood sent to Podesta in December 2015 in which the CNBC host wrote that he imagines President Barack Obama feels "some (sad) vindication" in suggesting that the Republican Party was "veering off the rails."

"I certainly am feeling that way with respect to how I questioned Trump at our debate," Harwood wrote.

Image source: WikiLeaks

Harwood, for his part, denied the commentator's charge in a one-word tweet on Monday.